NAIROBI, Kenya >> A U.S. congressional delegation has arrived in Kenya to meet with the new president-elect and the opposition figure likely to file a court challenge to his election loss in the latest electoral crisis for East Africa’s most stable democracy.

The new U.S. ambassador to Kenya, Meg Whitman, said the delegation led by Sen. Chris Coons also will meet with outgoing Kenyan President Uhuru Kenyatta, who has been publicly silent since the largely peaceful Aug. 9 election.

President-elect William Ruto is Kenyatta’s deputy president, but the two fell out years ago, and Kenyatta in the election backed longtime opposition figure Raila Odinga instead.

Odinga has said he is exploring “all constitutional and legal options” to challenge his close election loss. His campaign has a week from Monday’s declaration of Ruto’s win to go to the Supreme Court, which then has 14 days to rule. Odinga has urged his supporters to remain calm in a country with a history of post-election violence.

Kenya’s electoral commission publicly split in chaos just minutes before Monday’s declaration, with commissioners accusing each other of misconduct. The four commissioners who objected to Monday’s declaration were appointed by Kenyatta last year.

The split came as a shock to many Kenyans after an election widely seen as the country’s most transparent ever, with results from the more than 46,000 polling stations posted online for the public to follow along. Public tallies, including one by a local election observer group, added up to a Ruto win with just over 50% of the votes.

The political transition in Kenya will have significant impact on the East Africa region, where Kenyatta had been working with the U.S. to try to mediate in Ethiopia’s Tigray conflict and promoting peace efforts between Rwanda and Congo. Ruto in his public comments this week has focused on domestic matters, not regional ones.

The 55-year-old Ruto appealed to Kenyans by making the election about economic differences and not the ethnic ones that have long marked the country’s politics with sometimes deadly results. He portrayed himself as an outsider from humble beginnings defying the political dynasties of Kenyatta and Odinga, whose fathers were Kenya’s first president and vice president.

The 77-year-old Odinga has pursued the presidency for a quarter-century. He is renowned as a fighter and was detained for years in the 1980s over his push for multiparty democracy. He was also a supporter of Kenya’s groundbreaking 2010 constitution.